Open Postcode Ireland

Version 4 Grid

Redesigned in 2015, version 4, is a spiral of its 25 characters starting with 2 in the bottom left and continuing clockwise to X in the middle. X will always be the centre. The letter V has been removed as too vowel-like in print and replaced with B, which is now uppermost top-right so as to place any B codes firmly within the UK postcode area BT and avoid any possible confusion. Examples in other pages of documentation here are still using version 3 so are incompatible with the updated demo map and app. The algorithm is the same but uses the alphabet "6789B5NPQC4MXRD3LWTF2KJHG".

About the Open Postcode

A fully extensible, independent, free and open geolocation code for a wide range of applications and precisions, efficiently describing single points and complex areas (released under the LGPL).

Born as a proof of concept that geolocation-postcodes can be trivial maths, and without the need for proprietary licenses and centralised management, it remains Ireland's most accurate postcode at 8 characters; while even at 7 characters at <3m average radial offset from a point - over 4 times more precise than Loc8code. For geolocation applications: at eight characters it extends to an accuracy of an average radial offset of ~.58m (inside an area just 1.2m x .92m), while the code is easily extended with even further characters. At 9 characters it is down to centimetre scale. At 10 characters it can provide geolocation coding for the entire globe.

On the whole locations nearby have similar codes. City Hall, Dublin, is at D4H9-G73. The Central Bank is at D4HB-LH. The National Concert Hall is at D4HD-C6. The DCENR on Adelaide Road is D4G4-3B. While a house on the Blaskets is 2758-QR.

It is short, as short as any other and as short as you need it to be.

It is clear, avoiding character confusion.

Easy to remember, while neighbouring codes are largely similar.

It is accurate, to an average distance of under 3m at 7 characters.

It is scaleable and extensible to any application or purpose from 1 character to 10 characters capable of covering the globe.

It is flexible, not just about mail and addresses, but for all sorts of locations, points-of-interest, postboxes, railway bridges, TV masts, telephone poles, pylons, manholes, petrol stations, lay-bys, in fact any geolocation data.

It does not categorise. It does not navigate. It just points (navigation is for other systems).

Each postcode is verifiable as correct by a built in checksum character.

It has a published mathematical algorithm, free to use and to adapt, based on earth coordinates.

Format: The code does not prescribe a format for display for individual codes. It is open to the specific application to apply formatting rules. For example, a postcode might prescribe the format D4TG-HK5 to delineate postal areas and specific addresses.

Precision: The code is open to any number of uses and required precision, depending on the purpose it can have any number of required characters. It is Ireland's more precise code available.

Parameters: The parameters for an Irish postcode as set via "west=-10.75; north=55.5; wide=5.4; high=4.2; digits=7". Using the code on a world scale generates a geolocation code in 10 just characters. Likewise, the OpenPostcode for Hong Kong is defined by "west=113.8; north=22.6; wide=.7; high=.5; digits=6".

Checksum: A checksum character is available at any precision level of the code.